Unit 2_Intro to Sensory Systems

Question 1

Where does perception begin?

Answer 1

At the receptor level

Question 2

What triggers an electrical signal in a sensory receptor?

Answer 2

A stimulus

Question 3

Once a stimulus triggers an electrical signal in a sensory receptor, information is then relayed/processed from cell to cell with the ultimate goal of reaching the cortex for what?

Answer 3

conscious perceptions

Question 4

It is important to note sensations are needed to trigger responses like what?

Answer 4

reflexes, movements, and alertness

Question 5

Almost all sensory information is sent to the cerebral cortex for perception via what?

Answer 5

The thalamus (Smell is the exception)

Question 6

This large ovoid mass is the largest of the four components and each half of the brain contains one. In many individuals there is a short inter-thalamic adhesion that connects the two thalami across the third ventricle that lies between them. Contains nuclei that may be divided into 5 functional nuclear groups.

Answer 6

Thalamus

Question 7

What comprises the nuclei of Group 1 - Sensory Group?

Answer 7

1. lateral geniculate (LG) – Eye
2. medial geniculate (MG) – Ears
3. ventral posterolateral (VPL) – Body
4. ventral posteromedial (VPM) - Face

Question 8

These nuclei have connections with the basal ganglia and the cerebellum and are involved in motor control?

Answer 8

GROUP 2 – Motor Group

Question 9

These nuclei have important connections with limbic system structures and are involved in emotions such as anxiety and also in memory?

Answer 9

GROUP 3 – Limbic Group

Question 10

These nuclei are likely involved in the complex processing of sensory information?

Answer 10

GROUP 4 – Multimodal Group

Question 11

Recent evidence suggests that these nuclei are involved in the regulation of consciousness along with roles in movement control and pain?

Answer 11

GROUP 5 – Intralaminar Group

Question 12

What kind of neurons are sensory nerves?

Answer 12

Pseudounipolar

Question 13

Sensation is transmitted via what type of nerves?

Answer 13

Peripheral nerves

Question 14

The morphological distinction between _______ and _______ is blurred.

Answer 14

Axons
Dendrites

Question 15

Where are cell bodies residing in the peripheral nervous system for sensory neurons?

Answer 15

Ganglions in the spinal cord

Question 16

Having myelin on the peripheral nerve will do what?

Answer 16

Decrease capacitance and allow EPSP or IPSP to have same magnitude when it reaches cell body

Question 17

What is a specialized cell or group of cells that transform a type of physical energy into an electrical signal?

Answer 17

Somatosensory Receptors

Question 18

What are two structure types of Somatosensory Receptors?

Answer 18

Free nerve ending

Special receptor cell

Question 19

A sensory neuron in a sensory ganglion whose peripheral process is specialized for reception?

Answer 19

Free nerve ending

Question 20

A sensory neuron in a sensory ganglion whose peripheral process is connected to what?

Answer 20

Special receptor cell

Question 21

Axons (fibers) with the largest diameter and most myelin have the greatest what?

Answer 21

conduction velocities

Question 22

Axons (fibers) with the smallest diameter and little or no myelin have the slowest what?

Answer 22

conduction velocities

Question 23

Axonal conduction velocity is inversely related to what?

Answer 23

Axonal resistance (Ra) and Axonal Capacitance (Cm)

Question 24

Small diameter axons have what?

Answer 24

high resistance

Question 25

Unmyelinated axons have what?

Answer 25

high capacitance

Question 26

Large diameter axons have what?

Answer 26

low resistance

Question 27

Myelinated axons have what?

Answer 27

low capacitance

Question 28

Peripheral nerves contain what?

Answer 28

Both myelinated and unmyelinated axons

Question 29

Axons associated with skin are named differently than what?

Answer 29

Those associated with muscle

Question 30

The amount of stimulus relate to what?

Answer 30

Types of fibers being triggered

Question 31

How are receptors classified?

Answer 31

based on the form of energy or chemical to which they respond

Question 32

What receptors respond to mechanical deformation, detect vibration, tapping, pressure, stretch, etc., connected to Group I (a and b) Group II (A beta), and Group III (A delta) nerve fibers?

Answer 32

Mechanoreceptors

Question 33

What receptors respond to the presence of certain molecules, detect chemical changes such as glucose, oxygen and carbon dioxide changes in blood, connected to Group IV (C) nerve fibers?

Answer 33

Chemoreceptors

Question 34

What receptors respond to non-painful temperature changes, warm receptors, cold receptors, connected to Group III (A delta) and Group IV (C) nerve fibers?

Answer 34

Thermoreceptors

Question 35

What receptors are not necessarily responsive to one type of energy, but respond when the magnitude is sufficient to begin to cause tissue damage, connected to Group III (A delta) and Group IV (C) nerve fibers?

Answer 35

Nociceptors

Question 36

What respond to light energy and are not connected to the Group 1-IV (A-C) nerve fibers but to specialized retinal ganglion axons?

Answer 36

Photoreceptors (rods and cones)

Question 37

What convert physical and chemical energy into electrical signals through a process called transduction?

Answer 37

Receptors

Question 38

What process is the following: 1. local event (stimulus) at a receptor leads to a change in membrane conductance for specific ions (Na+, K+). The result is a net movement of + charge into the cell leading to a decrease in membrane potential or depolarization. 2. depolarizes the receptor membrane and produces a RECEPTOR or GENERATOR POTENTIAL (these will be summed for action potentials).

Answer 38

Transduction

Question 39

What are a local graded potential which are dependent on the stimulus intensity and may be subthreshold, threshold, or suprathreshold? The amplitude of this potential is proportional to the stimulus intensity.

Answer 39

Receptor potentials

Question 40

The potential will be transmitted around the receptor membrane until it reaches the beginning of what? This area contains the voltage gated channels where, if the receptor potential is large enough and reaches threshold, it will generate an action potential which propagates down the peripheral nerve towards the CNS.

Answer 40

The distal end of axon or first node of Ranvier (if axon is myelinated).

Question 41

CNS identification of a stimulus intensity is done by what?

Answer 41

frequency coding and population coding

Question 42

What occurs with stimulus intensity; amplitude of receptor potential; frequency of action potentials to CNS all increase linearly?

Answer 42

Frequency (rate) coding

Question 43

What occurs when stronger stimuli activate more receptors which activate more axons (fibers) which tells CNS that the intensity has increased?

Answer 43

Population coding

Question 44

What occurs when each type of receptor usually only responds (easily; i.e. there is best stimulus) to one stimulus type?

Answer 44

Receptor specificity

Question 45

What is the organization of central nervous system pathways that describes a relationship between a particular part of the body and a particular area of the brain (SENSORY MAP)?

Answer 45

Somatotopy

Question 46

What are the basis of topography?

Answer 46

Receptive fields

Question 47

What is the spatial domain (e.g., where on skin) of a sensory neuron in the sense organ where stimulation excites or inhibits the neuron?

Answer 47

The receptive field

Question 48

What are small in areas such as the fingers and face, and huge in areas that don’t require much precision such as the back and thigh?

Answer 48

Receptive fields

Question 49

What refers to the organization of central nervous system pathways that describes a relationship between a particular part of the body and a particular area of the brain (really CNS since spinal cord has this kind of organization)?

Answer 49

Somatotophy

Question 50

What is a precise mapping of the projections at each station on each sensory pathway that enables our cortex to localize a sensory experience? It allows the CNS to encode for the localization and quality of the stimulus.

Answer 50

The sensory map - homunculus

Question 51

What suggests that no matter how you stimulate a pathway you will have the same perception?

Answer 51

Labelled line theory

Question 52

What occurs when receptor potential decreases in amplitude in response to constant maintained stimuli?

Answer 52

Adaptation - slowly adapting receptors and rapidly adapting - rapidly adapting receptors = better detection of changes in environmental stimuli

Question 53

What is the lowest stimulus intensity that a subject can detect?

Answer 53

Absolute Sensory Threshold Thresholds are NOT FIXED (can be raised or lowered)

Question 54

What help shape more complex receptive fields within CNS?

Answer 54

Interneurons